I rarely plan out the exact number of chapters a story will need. Once I get a ballpark estimation in my head, I either try to figure out how a story will end, or I don’t, and rush in.
As far as chapter length goes…for long fiction I have a rule of thumb (not an iron law) I use that I picked up from some place else, I can’t remember where. That rule is: At least one important plot point per chapter. What I mean by that is, try to have the story take a significant step forward with every chapter, and if a subplot or two gets advanced along the way, so much the better.
Don’t worry about chapter lengths being consistent throughout a fic, readers won’t care for the most part about uneven lengths as long as the chapters are effective. Unless the size difference is extreme (like 200 words for one, 8000 for the next). I find a well developed chapter is difficult to do in under 1000-2000 words, but there are always exceptions.
As far as ending chapters, try to alternate cliff-hanger endings (if you like to write them) with uhh…non-cliff-hanging endings. Even if a chapter ending is not a cliffhanger, try to end on a strong thought or image or scene, and don’t linger. Leave the aftermath for a later chapter.
For example, if you want a chapter to end with a college student getting fed up and shouting at his pushy professor, try ending it with the last sentence describing the door slamming shut behind the student as he storms out. Don’t even show the professor’s reaction just yet, make the reader got to the next chapter to find out.